Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx agentmods add skills/ericrisco/rsc-harness/observabilitynpx skills add ericrisco/rsc-harness --skill observabilitygit clone --depth 1 https://github.com/ericrisco/rsc-harnessWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/ericrisco/rsc-harness/observability)<a href="https://agentmods.dev/skills/ericrisco/rsc-harness/observability"><img src="https://agentmods.dev/badge/skills/ericrisco/rsc-harness/observability.svg" alt="Measured on agentmods" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5 | $0.00070 | $0.03649 |
| Opus 5 | $0.00035 | $0.01825 |
| Sonnet 5 | $0.00014 | $0.00730 |
| Haiku 4.5 | $0.00007 | $0.00365 |
Grade A, and why
observability scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 236 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Observability
You are wiring the inside view of a service: when something breaks at 3am, an engineer must be able to answer "what happened, where, and why" from telemetry alone — without adding a console.log and redeploying into the fire. This skill emits a concrete artifact: SDK init code, instrumentation (spans/metrics/structured logs), a Collector config, and alert rules that the instrumentation makes possible. The outside-in half — is it up, who gets paged — is ../monitoring/SKILL.md.
The one rule
Every signal carries the same correlation identity: trace_id, service.name, deployment.environment. A log line you cannot pivot to its trace, or a spiking metric you cannot pivot to an exemplar span, doubles your mean-time-to-resolution — you are back to grepping. Three signals that don't share keys are three disconnected tools; three that do are one queryable system. Set the resource once at SDK init, inject trace_id/span_id into every log, and never emit a metric you can't tie back to a service and environment.
Start from the operator's questions
Before choosing signals, write two to four questions on-call must answer during the likely incident. For example: “Are payment retries recovering?”, “Which dependency and failure class drives exhaustion?”, “Can one payment be charged twice?”, “Which customer-visible operations need intervention now?” Then assign the cheapest signal: metrics say that/how much, traces show where/causal path, logs explain why for this event. If a proposed event or label answers none of the questions, do not emit it.
The three pillars — when each earns its place
Don't emit all three of everything. Each signal answers a different question at a different cost.
| Signal | Answers | Cost | Alert on it? | Main gotcha |
|---|---|---|---|---|
| Logs | "what exactly happened in this one event" | high per-event, cheap to skip | rarely (noisy) | high-cardinality fields belong in the body, not in stream labels |
| Metrics | "what's the rate/aggregate over time" | cheap, pre-aggregated | yes — this is your alert source | cardinality explosion if a label is unbounded |
| Traces | "what was the causal path across hops, and where did time go" | medium; sample it | indirectly (via derived RED metrics) | one giant span = no causality; sample or you pay for noise |
What ships with it
5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- yesterday First seen · 236 lines · 70 tokens per session scan A 15559bd221a5
observability is a skill published in the GitHub repository ericrisco/rsc-harness (64 stars, last pushed 2d ago), licensed MIT. It adds 70 tokens to every session and 3,649 once invoked, about $0.0003 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-03.
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